This research will investigate the mechanisms by which bacteria acquire the enzymatic abilities to permit them to utilize novel and uncommon chemicals as growth substrates. Specifically studied will be the ability of organisms in the genus Klebsiella to develop efficient metabolic pathways to permit them to survive and multiply when presented with certain unnatural carbohydrates as sources of energy and carbon. Using the present knowledge, that regulatory mutations permit Klebsiella to utilize the pentoses D-arabinose and xylitol as growth substrates, attempts will be made to develop an efficient, regulated, catabolic pathway for the degradation of D-arabinose. Chemostat studies employing D-arabinose as a substrate, will be used to test experimentally the concepts of genetic drift, gene duplication and gene translocation. Experiments will continue with chemostats using xylitol as a limiting carbon and energy source in an attempt to confirm the hypothesis that the increases in ribitol dehydrogenase observed in mutants of K. aerogenes obtained from such chemostats is the result of duplication of the structural gene for that enzyme.